Let me suggest yet another way -- use config generated by vzsplit 1. 
You'll have something very close to "unlimited" but without deficiency 
#3 pointed to by Kirill.

Kirill Korotaev wrote:
> You just need to set maximum values to barrier/limits and VM will be essentially uinlimited.
> Check /proc/user_beancounters to see how host VM is limited with "unlimited" values (i.e. highest possible
> limit value).
>
> 3 notes:
> 1. max limit is different on x32 and x64 machines
> 2. both barrier and limit must be set to these values.
> 3. in such a configuration if a global memory shortage happens out-of-memory
>    killer kills some app as in native Linux system.
>
> Thanks,
> Kirill
>
> Steve Wray wrote:
>   
>> No answers? Its been a while...
>>
>> We have a bunch of openvz VMs, nothing 'in production'. The host has 4G
>> of RAM. I want all the VMs to have access to 4G of RAM and all the
>> sockets and other stuff that they may need at any time; I don't have
>> time to carefuly tune the parameters of all of them to just what they
>> need and no more.
>>
>> I don't mind or care that they are over-committed I just want them to
>> have max resources.
>>
>> Thanks
>>
>> Steve Wray wrote:
>>     
>>> Hi there,
>>>
>>> I have a server running OpenVZ with several VMs running on it.
>>>
>>> At the moment I have to specify various limits to each VM
>>> configuration and, when they hit their limits strange things can happen.
>>>
>>> Ideally I'd let them all have full access to all the resources
>>> available on the physical server. They can fight it out among
>>> themselves if they want to compete for the resources. Most of these
>>> VMs are quiescent and not actually doing much at all most of the time
>>> anyway.
>>>
>>> I've not been able to figure out how to configure OpenVZ like this
>>> though. Is it something I have to set in each VM config file? Or is it
>>> a server-wide thing?
>>>
>>> Any ideas?
>>>
>>> Thanks!